Mapping undersea dunes near San Francisco

Using sonar devices and some high tech 3D gadgetry, researchers at the USGS mapped large undersea sand dunes that are present on the ocean floor near San Francisco. These sand dunes are up to 30 feet high and extend for upwards of 700 feet. They are located where the bay meets the Pacific Ocean, near the Golden Gate Bridge.
The purpose of the survey was to help researchers better understand coastal erosion, as well as characterize changes that have happened in the bay over the last 50 years.

Scientists previously mapped parts of the bay two years ago in order to look at the distribution of bed forms (dunes) within the bay itself, as well as image a waste disposal area south of Alcatraz that is used to dump sediment dredged up from the bottom of the bay.